1. Field of the Invention
The present invention relates to a dynamoelectric stator such as for an automotive alternator, etc., and a method for manufacturing a dynamoelectric stator, and particularly to a stator and a method for manufacturing a stator wherein adhesion of varnish to radially-outer first and second axial end portions of a stator core is suppressed.
2. Description of the Related Art
Conventional automotive alternator stators include: a cylindrical stator core in which slots opening radially inward are arranged at a predetermined pitch circumferentially; and a stator winding installed in the stator core, and are mounted such that radially-outer first and second axial end portions of the stator core are held from first and second axial ends by a front-end bracket and a rear-end bracket. (See Patent Literature 1, for example.) Annular varnish supporting members made of a glass-reinforced epoxy resin are mounted radially inside coil end groups of the stator winding, and varnish is dripped from radially outside the exposed coil end groups. Here, the varnish is prevented from leaking radially inside the coil end groups by the varnish supporting members. Thus, problems such as the rotor sticking to the stator core, etc., which arise as a result of the varnish leaking radially inside the coil end groups, are prevented.
In conventional methods for manufacturing stators, air is also blown toward outer peripheral portions of the coil end groups (radially outward) while dripping the varnish so as to prevent the varnish from adhering to first and second axial end portion surfaces of the stator core. (See Patent Literature 2, for example.)
Patent Literature 1: Japanese Patent Laid-Open No. 2004-187469 (Gazette)
Patent Literature 2: Japanese Patent Laid-Open No. 2004-194398 (Gazette)
In automotive alternators, only a slight gap is present between radially-inner surfaces of the stator and radially-outer surfaces of the rotor. Thus, when a varnish supporting member is disposed in a ring shape radially inside the coil end groups as in conventional automotive alternator stators, there has been a risk that a delay in the rotational action of the rotor may be caused if deformation or tearing occurs in the varnish supporting member. Furthermore, because the varnish is applied by being dripped from radially outside the coil end groups, the varnish also adheres easily to the radially-outer first and second axial end portions of the stator core, which constitute a stator supporting portion. Thus, there has been a risk that the stator supporting portion may lose its flatness if the varnish adheres to the radially-outer first and second axial end portions of the stator core, preventing the stator core from being held from the first and second axial ends by the front-end bracket and the rear-end bracket.
In conventional methods for manufacturing stators, because air is blown toward radially-outer sides of the coil end groups while the varnish is being dripped onto the coil end groups, varnish that has adhered to the first and second axial end surfaces of the stator core is blown off by the air, preventing the varnish from adhering to the radially-outer first and second axial end portions of the stator core. This varnish functions to fix conductor wires constituting the coil end groups to each other, and also enters the slots to fix the conductor wires inside the slots to the slots. However, because the air blows the varnish toward an outer periphery of the coil end groups, the varnish crosses the conductor wires of the coil ends and is less likely to enter the slots. As a result, another problem has been that the varnish must be dripped excessively, reducing varnish usage efficiency. Furthermore, because the varnish is blown off the coil end groups and adheres to the air nozzle and other equipment, yet another problem has been that maintenance is troublesome and expensive.